Background: Multiple published quantitative systematic reviews have reported on adverse events associated with the use of sodium glucose co-transporter 2 (SGLT-2) inhibitors in patients with type 2 diabetes mellitus. Aims: To summarize and appraise the quality of evidence from quantitative systematic reviews assessing adverse events of SGLT-2 inhibitors. Methods: We searched PubMed, EMBASE and the Cochrane Library for quantitative systematic reviews assessing SGLT-2 inhibitor safety. Two reviewers extracted data and assessed methodological quality using the Assessment of Multiple Systematic Reviews 2 (AMSTAR 2) tool. Main outcomes included pooled and single study point estimaates (in the absence of pooled estimates) with corresponding 95% confidence intervals (CIs) of SGLT-2 inhibitors versus placebo or active comparators for genitourinary infections, volume depletion, acute kidney injury, bone fractures, diabetic ketoacidosis, lower limb amputations, cancers, and other notable adverse events. Results: Out of 1289 citations screened, 47 reviews assessed SGLT-2 inhibitor safety, of which 35 were of low quality. Canagliflozin, dapagliflozin and empagliflozin were consistently associated with an increased risk of genital tract infections versus placebo (point estimates ranged from 2.5 to 9.8) and other antihyperglycemic agents (point estimates ranged from 2.7 to 12.0). Canagliflozin and dapagliflozin were associated with an increased risk of diabetic ketoacidosis. Canagliflozin was the only agent associated with an increased amputation risk; however, this was driven by results from a single trial program. Dapagliflozin was the only agent that exhibited a statistically significant increased risk of urinary tract infections. Empagliflozin was associated with a statistically significant increased risk of bladder cancer; however, this finding was susceptible to detection bias. None of the agents were associated with a statistically significant increased risk of acute kidney injury, or bone fractures compared to placebo or mixed (active or placebo) comparators. Upper 95% CI limits do not rule out clinically meaningful outcomes. Conclusion: The majority of quantitative systematic reviews reporting on adverse events of SGLT-2 inhibitors were of low methodological quality. Despite almost 50 quantitative systematic reviews published on the safety of SGLT-2 inhibitors, clinicians are still left uncertain of the risks of important adverse effects. Plain Language Summary SGLT-2 iInhibitor side effects: overview of reviews Many published systematic reviews have reported on side effects associated with the use of sodium glucose co-transporter 2 (SGLT-2) inhibitors in patients with type 2 diabetes. We aimed to summarize and appraise the quality of evidence from quantitative systematic reviews assessing side effects of SGLT-2 inhibitors. Using the Assessment of Multiple Systematic Reviews 2 (AMSTAR 2) tool, two authors extracted data and assessed the methods of included reviews. Main outcomes included reported pooled and single study point estimates for several SGLT-2 inhibitor side effects such as genital infections, bone fractures, lower limb amputations, increased blood acidity, among others. Of the reviews included in our study, 35 of the 47 reviews assessed were of low quality. Canagliflozin and dapagliflozin were associated with an increased risk of blood acidity in a 2020 review. Canagliflozin was the only agent associated with an increased amputation risk; however, this was driven by results from a single trial program. Dapagliflozin was the only agent that exhibited a significantly increased risk of urinary tract infections. Empagliflozin was associated with an increased risk of bladder cancer; however, this finding was susceptible to bias. None of the agents were associated with an increased risk of kidney injury or bone fractures.

Evidence from observational studies may be considered complementary to that of randomized controlled trials (RCTs), particularly when assessing rare outcomes of drug therapies. The sodium glucose co-transporter-2 (SGLT-2) inhibitors are a novel class of antidiabetics that has been linked to an increased risk of diabetic ketoacidosis (DKA). In this study, we conducted a systematic review and meta-analyzed data from RCTs (n=18) and observational (n=7) studies separately, to assess the consistency of the magnitude of association between SGLT-2 inhibitors and DKA. We also illustrate the strengths and weakness of the two designs. Results from RCTs and observational studies consistently show almost a doubling in the risk of DKA in patients using an SGLT-2 inhibitor compared to placebo or active comparator. Using a random-effects model, the pooled relative risk [RR], (95% confidence interval [CI]) was 2.08, (95%CI 1.28, 3.40) from placebo-controlled RCTs and was 0.82 (95%CI 0.25, 2.68) from active-comparator RCTs. The pooled adjusted hazard ratio from observational studies was 1.74, (95%CI 1.28, 2.38). Notably, the two designs complement each other in several domains, including external and internal validity and power. This demonstrates the need for both sources for a more comprehensive evidence when assessing rare adverse events.

Aims To summarize reported cancer events associated with SGLT‐2 inhibitors used in patients with type 2 diabetes mellitus, as well as assess the quality of included reviews. Materials and methods In May 2019, we searched PubMed, Embase and the Cochrane Library for quantitative systematic reviews assessing the safety of SGLT‐2 inhibitors. Data were abstracted using a standardized form, and methodological quality was assessed using the AMSTAR 2 tool. Main outcome measures included total cancer events and specific cancers such as breast cancer, bladder cancer, gastrointestinal cancer, prostate cancer, respiratory cancer, renal cancer and skin cancer. Pooled treatment effects from included reviews were summarized for SGLT‐2 inhibitors as a class and for individual SGLT‐2 inhibitors commonly used worldwide (canagliflozin, dapagliflozin and empagliflozin). Results We screened 1248 unique citations, of which eight quantitative systematic reviews meta‐analysed results from studies reporting the association between an SGLT‐2 inhibitor and any cancer. Only one review was rated as high quality according to AMSTAR 2 assessment. In total, data from 170 cancer‐related point estimates (PE) were reported. As a class, SGLT‐2 inhibitors were not associated with an increased risk of any cancer event versus placebo and active comparators. Most point estimates (7/143) were nonsignificant for individual cancers except for two associations. Empagliflozin was associated with an increased risk of bladder cancer versus placebo and active comparators in two reviews, while canagliflozin appeared protective for gastrointestinal cancer versus placebo and active comparators in one review. Conclusions It appears that SGLT‐2 inhibitors are not associated with an increased risk of total cancer or specific cancers in patients with type 2 diabetes. However, higher quality evidence is needed to derive confident conclusions.

IntroductionTo assess the comparative effectiveness and safety of renal-related outcomes associated with sodium-glucose cotransporter-2 inhibitors (SGLT2-i) initiation among patients with type 2 diabetes using real-world data.Research design and methodsWe conducted a population‐based cohort study using administrative healthcare data from Alberta (AB), Canada and primary care data from the Clinical Practice Research Datalink (CPRD), UK. From a cohort of new metformin users, we identified initiators of a SGLT2-i or dipeptidyl peptidase-4 inhibitor (DPP4-i) between January 1, 2014 and March 30, 2018 (AB) or between January 1, 2013 and November 29, 2018 (CPRD). Initiators of an SGLT2-i or DPP4-i were followed until death, disenrolment, therapy discontinuation, or study end date. The effectiveness outcome was renal disease progression, defined as a composite of new-onset macroalbuminuria, serum creatinine doubling with estimated glomerular filtration rate of ≤45 mL/min/1.73 m2, renal replacement therapy, hospital admission or death from renal causes. The safety outcome was hospitalization due to acute kidney injury (AKI). We adjusted for confounding using high-dimensional propensity score matching and estimated HRs using Cox proportional hazards regression. Aggregate data from each database were combined by random-effects meta‐analysis.ResultsAmong the 29 465 included patients (20 564 AB, 8901 CPRD), 37.5% were new SGLT2-i users in AB and 21.3% in CPRD. Compared with DPP4 initiators, SGLT2-i initiators were associated with a reduced risk of renal disease progression (pooled HR 0.79, 95% CI 0.62 to 1.00); however, there was no significant difference in the risk of AKI (pooled HR 0.89, 95% CI 0.58 to 1.36). These findings were consistent with other exposure definitions and antidiabetic comparators.ConclusionsOur findings support a renoprotective effect of SGLT2-i without an increased risk of AKI, compared with clinically relevant active comparators.

Aims Disproportionality analysis is a common pharmacovigilance tool to detect safety signals of type 2 diabetes medications from spontaneous drug reporting databases. The aim was to demonstrate the impact of using active‐comparator restricted disproportionality analysis (ACR‐DA), wherein the reference group is restricted to reports with a clinically appropriate active comparator. Methods Using reports from the Food and Drug Administration Adverse Event Reporting System, we assessed if sodium/glucose cotransporter 2 (SGLT2) inhibitors are associated with higher reporting of 5 potential adverse events: acute kidney injury, genitourinary tract infections, diabetic ketoacidosis, fractures, and amputations. For each adverse event, we calculated the proportional reporting ratio (PRR) and adjusted reporting odds ratio (aROR [95% confidence interval, CI]) using 3 types of reference groups: no SGLT2 inhibitor (background risk reference), other diabetes drugs (therapeutic class reference), and dipeptidyl peptidase 4 inhibitors (active comparator reference). Results Based on ACR‐DA, we did not detect a safety signal for acute kidney injury (PRR 0.92 [0.81–1.04]; aROR 0.78 [95% CI 0.72–0.85]) or fractures (PRR 0.44[95% CI 0.17–1.15]; aROR 0.74 [95% CI 0.61–0.91]) associated with SGLT2 inhibitors compared to dipeptidyl peptidase 4 inhibitors. However, we detected safety signals for genitourinary tract infections (PRR 2.75[2.02–3.76]; aROR 2.54[2.26–2.86], diabetic ketoacidosis (PRR 63.85[39.37–103.53; aROR 91.49[70.66–118.48]), and amputations (PRR 52.60 [19.66–140.75]; aROR 22.64 [15.32–33.42]. Conclusion The use of the proposed ACR‐DA to detect safety signals of type 2 diabetes medications may reduce false positive safety signals through careful selection of the comparator which is expected to reduce channelling bias.